Fluoropolymer compositions containing urethane fluoropolymers which comprise ionisable groups are known from the prior art.
For example, WO 2010/000715 (SOLVAY SOLEXIS S.P.A.) discloses composition comprising at least a (per)fluoropolyether derivative which contains at least one fluorinated block and at least one urethane block of formula:—OC(O)—NH-E-NH—C(O)O—wherein E is a divalent hydrocarbon group, optionally comprising one or more aromatic rings. The fluorinated block may contain at least one functional block comprising at least one ionisable group, like a sulfonic acid group, a carboxy group or an amino group.
WO 2008/138927 (SOLVAY SOLEXIS S.P.A.) discloses compositions comprising (A) at least a (per)fluoropolyether derivative which contains at least one fluorinated block and at least one urethane block of formula:—OC(O)—NH-E-NH—C(O)O—wherein E is a divalent hydrocarbon group, optionally comprising one or more aromatic rings; (B) at least one fluorocarbon polymer comprising at least one perfluoroalkyl chain linked by ester moieties, urethane moieties and/or urea moieties; and (C) at least one crosslinking agent. The fluorinated block may contain at least one functional block comprising at least one ionisable group, like a sulfonic acid group, a carboxy group or an amino group.
However, these documents do not disclose or suggest compositions comprising (per)fluoropolyether derivatives with opposite charges, i.e. comprising at least one (per)fluoropolyether derivative comprising fluorinated blocks containing at least one ionisable anionic group and at least one (per)fluoropolyether derivative comprising fluorinated blocks containing at least one ionisable cationic group in a defined ratio of ionic equivalents, and curable groups. Furthermore, these documents do not teach or suggest using the compositions for preparing materials endowed with elastic and/or self-healing properties.
WO 2007/102993 (3M INNOVATIVE PROPERTIES CO) relates to surface active block copolymers, their use in the manufacture of a foam composition and articles comprising the polymerised foam composition. The fluorinated block polymers comprise a (per)fluorinated block and may also contain functional blocks typically having one or more polar groups, such as carboxy, sulphonic or amino groups. Also this document does not specifically disclose or suggest compositions comprising block copolymers containing functional blocks having opposite charges and at the same time curable groups.
WO 2010/028226 (ARROWSTAR LLC) discloses compositions for imparting water and oil repellency to fibers, the compositions comprising a fluorinated polyurethane having a plurality of ionisable groups. This document discloses in particular a mixture of a cationic fluorinated polyurethane, namely Fluorolink® 5032 polyurethane, and an anionic fluorinated polyurethane, namely Fluorolink® P56 polyurethane; the compositions further comprise an acrylic polymer and are in the liquid form. Example 2, in particular, discloses an aqueous composition containing 8.8% by weight Fluorolink® 5032 polyurethane and 30.0% by weight Fluorolink® P56 polyurethane.
From the Applicant's calculations, it appears that the two polymers are not present in a stoichiometric equivalent ratio of ionic groups with opposite charges. Indeed, the equivalent weight of Fluorolink® 5032 polyurethane is 0.25 eq/kg and the equivalent weight of Fluorolink® P56 polyurethane is 0.49 eq/kg; accordingly, in the compositions of example 2, the equivalent ratio between Fluorolink® 5032 polyurethane and Fluorolink® P56 polyurethane is calculated to be 0.2, while the equivalent ratio between Fluorolink® P56 polyurethane and Fluorolink® 5032 polyurethane is calculated to be 6.7.
Also, this document does not teach or suggest replacing water in the preparation of the above compositions and it does not teach or suggest submitting the compositions to cross-linking in order to obtain self-healable and resistant compositions.
U.S. Pat. No. 5,798,409, corresponding to EP 0784641 B (MINNESOTA MINING AND MANUFACTURING COMPANY) discloses both aqueous and non-aqueous two-part polyurethane compositions and optionally self-healable and scratch-resistant coatings prepared therefrom. In particular, the non-aqueous composition comprises a part A and part B, wherein part A may comprise a urethane prepolymer which may contain carboxylic acid functional groups and which has a defined average hydroxyl functionality and a defined hydroxyl equivalent-weight, while Part B contains a cross-linker from the group consisting of polyisocyanates, blocked polyisocyanates, and mixtures thereof and an organic solvent. The NCO:OH ratio of Part B to Part A ranges from about 0.95:1 to about 1.07:1. Part A is curable in the presence of blocked polyisocyanate crosslinker by application of heat or the presence of polyisocyanate crosslinker under staged curing conditions.
These compositions are said to provide a PUR having excellent scratch resistance and self-healability (reference is made in particular to par. [0020]). However, this document neither discloses nor suggests to prepare compositions containing two fluorinated ionizable PUR polymers having opposite charges and at the same time a curable group.
WO 2013/017470 (SOLVAY SPECIALTY POLYMERS ITALY S.P.A.) discloses self-healing polymer compositions comprising:    a) at least one fluorinated ionisable polymer (A), which comprises recurring fluorinated blocks and recurring functional blocks, each of said recurring functional blocks comprising at least one ionisable anionic group, and in which polymer (A) at least one of the said recurring functional blocks is comprised between two fluorinated blocks;    b) at least one fluorinated ionisable polymer (B), which comprises recurring fluorinated blocks and recurring functional blocks, each of said recurring functional blocks comprising at least one ionisable cationic group, and in which polymer (B) at least one of the said recurring functional blocks is comprised between two fluorinated blocks; wherein the ratio between the ionic equivalents of polymer (A) and the ionic equivalents of polymer (B) ranges from 1.1 to 0.9.
However, the polymers herein disclosed do not contain cross-linkable groups, as the groups deriving from acrylate or 2-alkyl acrylate are in the backbone of the polymer and hence are not free for crosslinking reactions.
WO 2014/090646 (SOLVAY SPECIALTY POLYMERS ITALY S.P.A.) relates to non-aqueous fluoropolymers compositions containing polyurethane (PU), polyester or polyacrylates polymers. These compositions, when not balanced (i.e. when the equivalent ratio between ionisable anionic groups of polymer A and ionisable cationic groups of polymer B is different from 1, in particular higher than 1.1 or lower than 0.9—also referred to as “unbalanced compositions”) can be further reacted with appropriate reactive monomers, such as for example epoxy monomers containing alkoxy-silane or acrylic groups. However, only the unbalanced compositions containing either free ionisable ionic or cationic groups can react with curable monomers and can be then submitted to cross-linking reactions, giving rise to cross-linked compositions. Differently, the non-aqueous compositions wherein the ratio between the ionic equivalents of polymer (A) and the ionic equivalents of polymer (B) in the dispersion ranges is 1:1 do not contain either free ionisable ionic or cationic groups and hence they cannot be reacted with curable monomers and cannot give rise to cross-linked compositions.
Thus, according to this patent application, it is not possible to obtain crosslinked final coatings with fully balanced formulation (i.e. wherein the equivalent ratio between the ionisable anionic groups of polymer A and ionisable cationic groups of polymer B is equal to 1).